The problem is similar to the one we confirmed in July with the AT&T version of Apple's newest smart phone. It can occur when you hold either version of the phone in a specific but quite natural way in which a gap in the phone's external casing is covered. The phone performs superbly in most other respects, and using the iPhone 4 with a case can alleviate the problem.

As with the AT&T iPhone 4, the tests were all conducted under highly controlled conditions. And like the AT&T iPhone 4, a $30 bumper case corrected the problem.